There is a large asteroid belt located between Mars and Jupiter.
Asteroids are also known as minor planets.
The largest know asteroid has a diameter of 1000 KM.
This is the asteroid known as "Ceres"
Asteroids are composed mainly of carbonaceous or silicate rock. Some also consist of rich metal material.
Many asteroids exist but only 5000 are plotted and named. (at time of print)
Some asteroids orbits cross the path of earth. DON'T HIT US!
Comets are visible to the naked eye, but most must be detected by telescope.
Comets are made up of dust and ice this is what leads scientists to call them "dirty snowballs"
It is believed that billions of comets orbit the sun hundreds of AU's away.
Occasionally comets will hit off course and be gravitational pulled toward the earth.
Comet tails are formed by material 'evaporating' as it speeds to the sun, these tails may become thousands of Km.
long. The tail always points away from the sun because it is pushed by the solar wind.
In 1986, five space probes observed Halley's Comet as it entered the inner solar system.
The Giotto spacecraft sent the first close up images of the comet, because of this scientists were able to see the irregularly shaped nucleus. (16 km by 8 km)
Each day earth is showered by dust and rock fragments from space.
Friction causes these fragments to break up and vaporize. Occasionally the fragments are large enough to burn up, glow, and become evident. (meteors)
Meteors are mistakenly called shooting stars now and again though they are not stars at all.
Rarely some are large enough that they will be able to strike earth's surface. (meteorites)
When these fragments contact earth scientists study them as Extraterrestrial material.